There are many products and constructions in which close-fitting parts must be joined together. These all involve fitting one piece partially or wholly within a second piece. Examples include joining two pieces of piping, and attaching grips to a variety of types of equipment such as fishing rods, golf clubs, motorcycles, tools, and the like.
For the attachment of grips to various types of equipment, it has been recently customary to secure a strip of pressure sensitive adhesive tape about the shaft, remove the tape's release liner to expose the adhesive, render the adhesive temporarily slippery by applying an organic solvent, such as, for example, mineral spirits or a related petroleum distillate, or trichloroethylene, and slide the grip over the adhesive. The solvent gradually evaporates to provide a strong adhesive bond between the grip and the shaft. The process is undesirable due to release of organic solvent vapors into the environment, personal exposure to liquid organic solvents, and hazards posed by flammable solvents. Alternative approaches include the use of solvent-based adhesives; two part structural adhesives; and hot melt adhesives which are applied to the shaft, followed by slipping the resilient grip over the "wet" or flowable adhesive. In yet another approach, heat moldable adhesives are employed.
One disadvantage of these methods is that adhesive is "squeezed" out when the close-fitting grip is slid onto the shaft and positioned. This is messy and time consuming to clean up. Additionally, the adhesive that is squeezed out is wasted. Furthermore, non-uniform bond lines can result, which can reduce adhesive strength. Moreover, when solvent-based adhesives are employed, there is still undesirable exposure to flammable organic liquids and organic vapors as described above. Further, when hot melt or heat moldable adhesives are employed, the use of heat is required.
Examples of hot melt adhesives for use in joining two parts together include those disclosed by Dellis in U.S. Pat. No. 4,785,495; and Stobbie et al. in U.S. Pat. No. 5,288,359. Stobbie also discloses that when an especially tight fitting joint is desired it is helpful to apply a lubricating aid, such as water or hydroxy compounds, to the interior-fitting part. A heat moldable adhesive for use in applying motorcycle hand grips is described by Dellis in U.S. Pat. No. 5,155,878.
Use of a water activated system would be desirable from the perspective that the use of heat or organic solvents could be avoided. However, typical water activated adhesives have their own disadvantages. Once a grip is slipped on, water is trapped between the two parts and long drying times, e.g., greater than 24 hours, are thus required before handling strength is reached. When water soluble adhesives are used there is an observed puddling or collection of liquid of the adhesive components when the grip is slid on. This "puddling" retards drying, and can result in inconsistent bond strength as described above.
Consequently, there exists a need for an adhesive tape that can be used to bond close fitting parts together without the: need to apply and remove organic solvents or without the need to apply heat to activate the adhesive.